Speed reduction means

DETAILED DESCRIPTION OF THE INVENTION An embodiment of this invention will now be described in reference to FIGS.
4 to 7.
Numeral 11 denotes a stationary body having a cylindrical recess 12 of a suitable depth.
Fifteen axial grooves 13 of semicircular cross-section are formed in the cylindrical wall of recess 12.
Further, in the center of the bottom wall of the recess 12 there is bored a hole 14 and at four corners of the stationary body 11 there are provided four threaded holes 15.
Reference, numeral 16 denotes an output rotary body of hollow cylindrical shape which is capable of being inserted into the recess 12 of the stationary body 11.
At the center of base 17 of the output rotary body 16 there is provided an output shaft 18 which can be inserted in the hole 14.
Further, in the cylindrical wall of the output rotary body 16 there are perforated thirty-two holes 19 which are regularly distributed about the periphery of the wall in two mutually staggered rows to form a uniform zig-zag pattern.
The two side edges of the output rotary body 16 are provided, respectively, with flange 20.
Numeral 21 denotes a steel ball in a primary set of balls, and each steel ball 21 is fitted in each hole 19.
Numeral 22 is a steel ball in a secondary set of balls to be fitted for axial displacement in each axial groove 13 of the stationary body 11.
Further, an input rotary body 23 is inserted into the output rotary body 16.
A shaft 27 of the input rotary body 23 is rotatably supported at both ends thereof by a shaft-carrying cavity 24 in the output shaft 18 and a center hole 26 of a disc-shaped cover plate 25.
As shown in FIG.
6 the input rotary body 23 consists of an oval driving plate 30 having a portion 28 of a larger diameter and a portion 29 of a shorter diameter.
In the corners of cover plate 25 there are perforated four holes 31 to correspond to four holes 15 in stationary body 11.
Thus, the cover plate 25 is secured to the stationary body 11 by a plurality of screws.
Upon the insertion of steel balls 21, 22 in the axial grooves 13 of the stationary body 11 as well as in the holes 19 of the output rotary body 16, the output rotary body 16 is inserted in the opening 12 of the stationary body 11, and the input rotary body 23 is inserted in the output rotary body 16